The present invention relates to an arrangement and a method for providing cordless mobility in a telecommunications system comprising a private network.
The invention also relates to an arrangement for providing cordless access to the services provided by an exchange also when a cordless phone is not within coverage of a radio exchange adjunct to the exchange. Sure an exchange may e.g. relate to a private branch exchange, a centrex etc. The invention further relates to a telecommunications system comprising a private network wherein cordless mobility is provided and wherein cordless access to services offered by e.g. a private branch exchange is provided.
In general a cordless portable telephone can access a private branch exchange and the services provided thereby in a way which is similar to that of a normal desk telephone using DTMF (Dual Tone Multiple Frequencies) signalling as long as the cordless phone is within the radio coverage of a radio exchange (radio switch) adjunct to the private branch exchange. If however the cordless telephone is not within radio coverage of a radio exchange adjunct to the private branch exchange it can not be used and the user instead has to use for example a PSTN (Public Switched Telephone Network) phone, a cellular phone or a desk phone in the private network. This means that the user has to change phones which is an apparent drawback since the user has to have at his disposal two different phones having two different directory numbers etc.
In a system described in WO 94/16531 is illustrated an arrangement for establishing telephone links in a communications system by call transmission. A connection is provided between a number of radio exchanges and mobility is provided between them. Here a link thus is provided between the already existing private network and the links provided therein. This implies that in order to support those links, the private branch exchanges have to fulfil a number of requirements. Signalling between nodes independently of the private branch exchange will not be achieved and since existing private branch exchanges are used for providing the connections, the services offered will be limited and it will not be possible to get access to all the extension services existing in each of the nodes of the private network.